David Cameron will resign if he loses Scotland. A Prime Minister who allows the break-up of the United Kingdom cannot suffer such a statement of no confidence and continue in office.

That much is understood in Downing Street, where a gnawing doubt about the referendum gets worse by the day. The vote takes place in five months this Friday. Angst rather than panic describes the feeling apparent among those involved â€“ but is it just a momentary loss of nerve, or a dawning realisation that something is seriously wrong?

That’s a pretty sensational revelation. I have my doubts, but iff Brogan is right, then it maybe worth reviewing the next Prime Minister market. If Cameron does resign in the wake of a Yes vote, then I think the next Tory leader (and ergo next Prime Minister) will come from the following four.

William Hague – I’ve always viewed him as the if Dave ever fell under a bus candidate. Will he want it? I suspect he may not, but in the scenario of Scotland seceding from the Union, he may.

Theresa May – Who has been quietly impressive at the Home Office, which had turned into a political graveyard for others, as a result, the bookies make it between her and Boris as favourites for the next Tory leader. (As an aside, given the scenario outlined above, I can’t see Boris being able to run in this leadership election)

George Osborne – Two years ago following the omnishambles budget, I would have thought Larry the Cat had a better chance at being next Tory Leader than George. But times change, his personal ratings and the economy have improved, as well at the Tory polling in the aftermath of the budget, it is not as outlandish as it seemed a few years ago.